Bumps on a Twig

I titled this photo "Proud Mama."  She's the big one on the left.  The nymphs, of which there were several dozen extending far to the right of the edge of this photo, remind me of little wind-up toys.  They'll probably be gathered on the oaks in my driveway for a few weeks, and I never tire of watching and photographing them.  Click on the photo for a closer look.  I've read that they rarely if ever harm the trees, and on my oaks there are only a couple of small clusters out at the branch tips.  They're much harder to spot than you might think from viewing this photo.  They're mostly about 14" long except the adults that may be slightly over 1/2".  They seem reluctant to fly, although they can.  In the coming days I'll probably pester them a bit to at least get them to spread their wings for a different view.